Along with a recent trend for high integration of a semiconductor device, a dimension of a pattern has been remarkably scaled down. For example, in case a DRAM (dynamic random access memory) is manufactured, a capacitor electrode of a cylindrical shape is required to be thinner, and it is required to be longer to increase capacitance.
In order to manufacture a cylindrical capacitor electrode, a storage node hole is first formed in a pattern on a silicon oxide film, e.g., a BPSG film or the like, which is previously formed on a surface of a substrate. Then, a conductive material such as TiN, polysilicon or the like is deposited on an inner surface of the storage node hole, thus forming the cylindrical capacitor electrode. Next, the silicon oxide film remaining around the capacitor electrodes is removed by etching. In this case, a wet etching using an etching solution such as a BOE (buffered oxide etchant), a DHF (diluted hydro fluoricacid) or the like is widely used to etch the silicon oxide film remaining around the capacitor electrode.
However, when the thin and long capacitor electrode is manufactured, the wet etching method causes the capacitor electrode to be inclined (so-called “leaning”). In other words, in the wet etching method, tensile force is generated between capacitor electrodes due to surface tension of the etching solution and, thus, the capacitor electrodes pull each other. As a result, the recent thin and long capacitor electrode can fall down.
To that end, there has been employed a method for providing a support film made of SiN or the like between the capacitor electrodes. In addition, an etching solution containing anionic surfactant is being developed to selectively remove the silicon oxide film remaining around the capacitor electrode while protecting the support film made of SiN or the like.
However, the method for forming a support film to prevent the leaning requires a film forming process for forming a SiN film or the like, which is not cost-effective. Further, in the case of the conventional wet etching method, it is difficult to selectively etch the silicon oxide film, so that the SiN film serving as the support film may be damaged by the etching.